Evaluation of Hydrologic Alteration and Opportunities for Environmental Flow Management in New Mexico October 2011 Photo: Elephant Butte Dam, Rio Grande, New Mexico; Prepared by The Cadmus Group, Inc. Courtesy U.S. Bureau of Reclamation U.S. EPA Contract Number EP-C-08-002 i Table of Contents Executive Summary ............................................................................................................................................................ 1 1. Introduction ................................................................................................................................................................ 3 2. Hydrologic Alteration Analysis Study Design ....................................................................................................... 5 What Sites Are Assessed? ............................................................................................................................. 5 What Drives Hydrologic Alteration? ........................................................................................................ 11 How Is Hydrologic Alteration Assessed?................................................................................................. 16 3. Results of Hydrologic Alteration Analysis ........................................................................................................... 19 Alteration of High Flow Events ................................................................................................................ 19 Alteration of Low Flow Events ................................................................................................................. 21 Ecological Implications of Hydrologic Alteration in New Mexico ...................................................... 23 4. Hydrologic Alteration and Watershed Health ..................................................................................................... 28 Aquatic Species of Concern ....................................................................................................................... 29 Clean Water Act (CWA) Impaired Waters ............................................................................................... 31 Watershed Condition .................................................................................................................................. 33 Riparian Condition ...................................................................................................................................... 36 Geomorphic Condition .............................................................................................................................. 37 Groundwater-Surface Water Connection ................................................................................................ 37 Agro-Ecosystem Health .............................................................................................................................. 39 Drought & Climate Change Vulnerability ................................................................................................ 41 5. Environmental Flow Management in New Mexico ........................................................................................... 44 6. Recommendations for Future Environmental Flow Analysis .......................................................................... 46 7. References ................................................................................................................................................................. 50 Appendix A. Notes on Analysis Methods .................................................................................................................... 54 Appendix B. IHA Output................................................................................................................................................ 56 Appendix C. Watershed Health Metrics ....................................................................................................................... 67 ii List of Figures Figure 1. Illustration of the 5 characteristics of the natural flow regime (magnitude, frequency, duration, timing, and rate of change) for high flow events. .......................................................................................................... 3 Figure 2. USGS hydrologic regions of New Mexico. .................................................................................................... 5 Figure 3. Topography and climate of New Mexico....................................................................................................... 6 Figure 4. Map of study sites. ............................................................................................................................................. 7 Figure 5. Location of dams, surface diversions, and groundwater wells within study watersheds. ..................... 11 Figure 6. Example of Range of Variability (RVA) data for San Juan River high flow magnitude....................... 18 Figure 7. Number of study sites with median date of annual peak flow in each calendar month.. ..................... 19 Figure 8. Monthly streamflow (top), annual peak flow (bottom left), and annual minimum flow (bottom right) for the San Juan River near Farmington site.. .............................................................................................................. 23 Figure 9. Monthly streamflow (top), annual peak flow (bottom left), and annual low flow duration (bottom right) for the Santa Fe River near Santa Fe site from 1914-2010.............................................................................. 24 Figure 10. Essential Ecological Attributes presented in the Framework for Assessing and Reporting on Ecological Condition .............................................................................................................................................................................. 28 Figure 11. Number of Species of Greatest Conservation Need (SGCN) within study watersheds. ................... 30 Figure 12. Impaired waters of New Mexico ................................................................................................................. 32 Figure 13. Developed lands within study watersheds. ................................................................................................ 34 Figure 14. Priority areas for protection of forest health ............................................................................................. 35 Figure 15. Comparison of riparian development and total watershed development within study watersheds. Development includes urban and agricultural land cover types. ............................................................................... 36 Figure 16. Average annual baseflow index for study watersheds ............................................................................. 38 Figure 17. Location of saline soils in study watersheds .............................................................................................. 40 Figure 18. Ratio of water use to water availability (water use ratio) within study watersheds. ............................. 42 Figure 19. Projected changes in precipitation and temperature in New Mexico through 2050 ........................... 43 iii List of Tables Table 1. Physical, hydro-climatic, and streamflow data record characteristics of study sites. ................................ 8 Table 2. Potential drivers of hydrologic alteration upstream of study sites. ........................................................... 12 Table 3. Hydrologic metrics considered for assessment of hydrologic alteration. Annual (water year) values of each metric are considered for hydrologic alteration analysis. .................................................................................. 17 Table 4. Direction of trend for high flow metrics with a statistically significant trend (at p≤0.1) ...................... 20 Table 5. Direction of trend for low flow metrics with a statistically significant trend (at p ≤ 0.1) ..................... 22 Table 6. Common ecological responses to hydrologic alteration ............................................................................. 25 Table 7. Environmental flow needs for study sites included in this report ............................................................. 48 Table 8. Ecological and hydrologic vulnerability scores ............................................................................................. 49 Table A-1. Median values of IHA parameter group 1 (magnitude of monthly water conditions) for each study site. ....................................................................................................................................................................................... 57 Table A-2. Median values of IHA parameter group 2 (magnitude and duration of annual extreme water conditions) for each study site. ....................................................................................................................................... 58 Table A-3. Median values of IHA parameter group 3 (timing of annual extreme water conditions; reported as Julian day of year), group 4 (frequency and duration of high and low pulses), and group 5 (rate and frequency of water condition changes) for each study site. .......................................................................................................... 59 Table A-4. Annual rate of change